Conventional semiconductor device formation is commonly performed in one or more process chambers which have the capability to process substrates (e.g., semiconductor wafers) in a controlled processing environment. To maintain process uniformity and ensure optimal performance of the process chamber, various conditioning operations are periodically performed. For example, in a physical vapor deposition (PVD) process chamber, one commonly used conditioning operation is a “burn-in” process, wherein a target disposed in the PVD process chamber is bombarded with plasma ions to remove oxides or other contaminants from the target prior to performing substrate processes. Another commonly used conditioning operation is a “pasting” process, wherein a covering is applied over material deposited on process chamber surfaces to prevent the material from flaking off the process chamber surfaces and contaminating the substrate during subsequent processes.
In both of the aforementioned conditioning operations, a shutter disk may be positioned via a transfer robot atop a substrate support disposed in the process chamber to prevent the deposition of any materials upon the substrate support. The shutter disk typically comprises a material having a mechanical stiffness sufficient enough to resist deformation due to the additional weight of the deposited material. For example, the shutter disk commonly comprises a metal alloy, such as stainless steel, or a ceramic, such as silicon carbide.
However, the inventors have observed that during a pasting process, the shutter disk heats up. Due to heat gradient and/or deposition on the disc, the shutter disk may develop stresses from a thermal mismatch between the top and bottom surfaces of the shutter disk, for example, causing the shutter disk to deform (e.g., bow up at the ends). This deformation creates a gap which results in plasma exposure to the substrate support through the gap. Metal deposition on the substrate support could lead to substrate wafer arcing, substrate wafer sticking and/or breaking, electrostatic chucking force reduction if the substrate support is an electrostatic chuck, etc.
In addition, shutter disks are often stored clear of the processing area and moved by buffer chamber robots into a desired position during use. In order for the robots to be able to handle the disks, the weight and thickness of shutter disks must be minimized. These lighter weight/lower thickness shutter disks deform more during the pasting and burn-in processes.
Various solution have been tried to address the aforementioned problems. For example, use of lower RF powers, longer cooling periods, and addition of a cooling gas to the backside of a shutter disk have been tried. However, the inventors have observed that none of these solutions sufficiently protected the substrate support from undesired material deposition.
Accordingly, improved shutter disk assemblies are provided herein.